Ms. Le Pen, 42, articulate and telegenic, is expected to try to broaden the party’s appeal by fighting a new host of enemies — including Islam — that she considers to be threats to France.

She takes over a party that has more than 12 percent support in the polls as the nation prepares for next year’s presidential race, in which she seems sure to run. That level of support could hurt President Nicolas Sarkozy if he cannot heal splits within his governing party, the center-right Union for a Popular Movement.

The popularity of the National Front and Ms. Le Pen is considered one of the reasons Mr. Sarkozy played on anti-immigration, anticrime and anti-Roma feelings last summer by expelling immigrants who had overstayed their visas and by initiating a debate on “national identity.”

Ms. Le Pen won more than two-thirds of the vote at the National Front conference in Tours to take over as leader.

Her father, 82, ran for president five times. He beat the Socialist candidate to make it into a final runoff against Jacques Chirac, then the incumbent, in 2002, which represented a high point for the party. Mr. Le Pen founded the group in 1972, and molded it into a party opposed to immigration and the European Union.

Ms. Le Pen has focused on France’s failure to integrate its Muslim immigrants and on what she says are the dangers of Islam. She also concentrates on preserving “French values.”

A version of this article appears in print on January 17, 2011, on page A8 of the New York edition with the headline: Le Pen’s Daughter Elected to Lead His Far-Right Party. Order Reprints|Today's Paper|Subscribe